As a headrest provided on an upper portion of a seat back of an automobile or the like, various head rests have been presented, such as a headrest enabling only adjustment of height without changing the front-and-rear position (hereinafter also referred to as “fixed head rest”).
For example, JP 5513693 B presents a head rest (hereinafter also referred to as “folding type head rest”) capable of being tilted (folded) forward with respect to the seat back when the head rest is not used. The folding type head rest is folded when the head rest is not used, to secure a wide backward view of the driver or the like, and prevents improper use of the head rest by causing the folded head rest to widely project from the front surface side of the seat back.
As a head rest, a head rest (hereinafter also referred to as “back-and-forth adjustable type head rest”) enabling adjustment of its front-and-rear position in its use has been presented. For example, JP 2006-523497 A presents a back-and-forth adjustable type head rest (hereinafter also referred to as “parallel link type head rest”) adopting a parallel link mechanism. In addition, JP 5710831 B presents a back-and-forth adjustable type head rest (hereinafter also referred to as “upward swing type head rest”) that is rotatably attached to the upper portion of a head rest stay, to enable adjustment of its front-and-rear position in its use, without adopting a parallel link mechanism. The back-and-forth adjustable type head rest enables adjustment of the front-and-rear position of the head rest in accordance with the posture of the seated person or the like, and enables proper adjustment of the space between the back of the head of the seated person and the front surface of the head rest.
By contrast, the fixed type head rest has disadvantages that the backward view of the driver or the like is not secured when the head rest is not used, and the front-and-rear position thereof cannot be adjusted in its use. The folding type head rest described above has a disadvantage that the front-and-rear position thereof cannot be adjusted in its use. The back-and-forth adjustable type head rest described above has a disadvantage that the backward view of the driver or the like is not secured in its use. The back-and-forth adjustable type head rest described above is switched between a locked state and an unlocked state with a riding past spring, and may malfunction. In addition, the back-and-forth adjustable type head rest requires special press such as fine blanking, when members forming the head rest are processed, and has a disadvantage of increasing manufacturing cost.